It is well known in the art to have cylindrical tube ends containing grooves that are forced on the end of polyethylene tubes. Such tubes are then assembled end-to-end by means of clamps circumscribing the grooves and hydraulically sealed by means of O-rings and otherwise. It is difficult to mechanically lock the tube end in place on the polyethylene pipe and to provide a hydraulic seal between the tube end and the polyethylene pipe due to the property of polyethylene of being impervious to adhesives. Some of the methods known in the art to provide a hydraulic seal as well as to retain mechanical integrity between the tube end and the polyethylene pipe are: (a) drive screws are placed through the wall of the tube end into the pipe to provide mechanical rigidity; (b) machining a groove into the polyethylene pipe at the location under the groove and to dispose epoxy cement into the machined groove to prevent deformation of the OD of the polyethylene pipe and to provide a hydraulic seal between the polyethylene pipe and the tube end; or (c) drill a series of holes in an annular row near one end of the tube end before or after forcing the tube end onto the polyethylene pipe. After the tube end is pressed onto the pipe, multiple short poly plugs are heat-welded to the outer surface of the polyethylene pipe through the prepunched or predrilled holes previously disposed through the tube end. An O-ring is placed between the tube end and the polyethylene pipe to provide a hydraulic seal.
All of the above designs have experienced failures with either or both the hydraulic seal and the mechanical locked integrity of the tube end on the end of the polyethylene pipe. Sometimes these failures are catastrophic in that the tube end forcefully blows off the end of the pipe due to internal pressure or exterior mechanical strain causing rupture of the integrity of the pipeline and, sometimes, a danger to those in the nearby vicinity. Accordingly, it would be desirable to have a tube end that provides both a mechanical locked interface and a hydraulic seal with the outside diameter of the polyethylene pipe such that the need for O-rings are dispensed with and provide a mechanical integrity up to and exceeding the integrity test pressures of the polyethylene pipe.